Harvard MCB Department news article on new research from Venkatesh Murthy and colleagues, co-first authors Alice Berners-Lee and Elizabeth Shtrahman, examining how odor mixtures are represented in the piriform cortex of mice while they learn to discriminate a unique target odor mixture from hundreds of other odor mixtures. They found that with time the target mixture becomes over-represented–meaning more neurons of this brain region become selective for the target odor mixture than they were at the onset. They also gained additional insight into how continued over-training, even after mice are experts, can help them to make more robust judgements when encountering more ambiguous odor mixtures later on.